Syrian television has announced the capture of Al-Hader, a former rebel stronghold in Aleppo Province, in the Syrian Army's second big victory in two days ahead of international peace talks.

Regime soldiers, supported by troops from Iran and the Shi'ite Hizballah militia, claimed to be in full control of Al-Hader, just 48 hours after regime forces broke a siege by the Islamic State group of the Kweyris air base in Aleppo Province.

The Syrian Observatory for Human Rights confirmed regime forces had taken control of large parts of Al-Hader, which had been largely controlled by Al-Qaeda affiliate Al-Nusra Front and other Islamist groups.

"The town is the biggest headquarters for rebel forces in southern Aleppo, and capturing it would bring the army closer to the key Aleppo-Damascus highway," observatory head Rami Abdel Rahman said.

The Britain-based monitoring group said both Syrian and Russian warplanes were carrying out strikes in the area.

"Today's advance is the most important strategic advance for Syrian regime forces since the Russians began their air strikes," Abdel Rahman said.